• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2006.05a
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• pp.99-102
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• 2006

We developed the electronic ballast for the street HID lames with the leakage current detection and circuit breaker function. By detecting the leakage current and breaking the system we are protected from the electric shock and the ballast is safe from the electric damage at the time of the continuous reignition state.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.55 no.4
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• pp.202-206
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• 2006

In this paper, an auto detection method of stator winding fault of small induction motor is suggested. The Park's vector pattern which is obtained from 3-phase current signal by d-q transforming, is very good to detect winding fault. Comparing the Park's vector pattern of testing motor with its of healthy motor, the Park's vector pattern of fault motor is became an ellipse and the asymmetry is increased by the winding fault series. So for detecting the dis-symmetry, id-filtered function, Min-value, and Max-value are suggested for auto detecting. Using LabVIEW programing, 3-phase healthy motor and several kind of winding fault motors are tested and the test results are shown that the suggested method can gives us a possibility of an auto detecting winding fault.

• Proceedings of the KIEE Conference
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• 1994.07a
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• pp.91-93
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• 1994

Recently, for improving the power supply reliability and for rationslizing maintenance, new maintenance and monitoring systems are stornagly desired for use in the field of electric power transmission. In this paper, we describes the optical fault detecting method of underground power transmission lines using bareearth doped YIG Faraday sensors which are very light, small size and fast response. As regarding, we use the zero phase current detecting algorithm at insulated joints.

• Proceedings of the KIEE Conference
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• 2005.07b
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• pp.1294-1296
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• 2005

Because of its cost effectiveness, the Brushless DC Motor(BLDCM) is focused by the industry these days. Considering the constant back-EMF region of the BLDCM, only a simple position information should be provided for constant torque control. From this point of view, using expensive position sensors, such as encoder, resolver, etc, decreases the cost effectiveness of the BLDCM. The Proposed detecting circuit detects position of zero crossing point(ZCP) then relative position could be calculated from ZCP. This circuit is robust to noise because of working in the current level. BLDCM is driven from the position information by the ZCP The reliability on BLDCM sensorless control using the voltage detecting circuit is shown through simulation using Matlab.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.55 no.6
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• pp.255-260
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• 2006

Arc Fault Current is an which occurrs in two opposite electrode. In this paper, arc current control algorithm is designed for the interruption of arc fault current which is occurred in the low voltage network. This arc is one of the main causes of electric fire. General arc current sensor has troubles for detecting arc currents, thus we would like to propose the arc current detection method without current sensor. In this parer, arc discharge currents within power lines are being detected through the arc current control algorithm.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.10 no.1
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• pp.90-95
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• 2014

Local wall thinning is a point of concern in almost all steel structures such as pipe lines covered with a thermal insulator made up of materials with low thermal conductivity(fiberglass or mineral wool); hence, Non Destructive Technique(NDT) methods that are capable of detecting the wall thinning and defects without removing the insulation are necessary. In this study we developed a Pulsed Eddy Current(PEC) system to detect the wall thinning of Ferro magnetic steel pipes covered with fiber glass thermal insulator and shielded with Aluminum plate. The developed system is capable of detecting the wall thickness change through an insulation of thickness 10cm and 0.4mm aluminum shielding. In order to confirm the thickness change due to wall thinning, two different sensors, a hall sensor and coil sensor were used as a detecting element. In both cases, the results show a very good change corresponding to the thickness change of the test specimen. During these experiments a carbon steel tube of diameter 210mm and a length of 620mm, which is covered with insulator of 95mm thickness was used. To simulate the wall thinning, the thickness of the tube is changed for a specified length such as 2.5mm, 5mm and 8 mm from the inner surface of the tube. A 0.4mm thick Aluminum plate was covered on the Test specimen to simulate the shielding of the insulated pipelines. For both hall sensor and coil detection methods Fast Fourier transform(FFT) was calculated using window approach and the results for the test specimen without Aluminum shielding were summarized which shows a clear identification of thickness change in the test specimen by comparing the magnitude spectra. The PEC system can detect the wall thinning under the 95 mm thickness insulation and 0.4 mm Al shielding, and the output signal showed linear relation with tube wall thickness.

• Proceedings of the KSR Conference
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• 2004.10a
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• pp.1390-1395
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• 2004

Recently, the load increasement and new regenerative systems of electrified railway system make it a difficult to distinguish between the load current and fault current. The failure of traction system perhaps causes over-current to flow. The high current can collapse other railway systems. If failures of the traction system takes place, the failures are detected and protected lest it should provoke high current flow. The over current from such a traction system failure permit to charge high tension voltage and produces high temperature arc, voltage instability, current cutting, and break down railway systems. The traction system failures detect and the system has to immediately cut off from over-current flow. To isolate the failure, the system can distinguish failure current from current flows. It forces us to adapt such as a new intelligent protection system. The protective system in traction system play a role of detecting and isolating failure points. In this paper, we proposed intelligent algorithm for discriminating normal and abnormal situation instead of the system being operated abnormally.

• Proceedings of the KIEE Conference
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• 2002.07b
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• pp.958-960
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• 2002

High Temperature Superconducting (HTS) devices make it possible to operate with no electrical loss by resistance. If, however, the applied current is over its critical current, the phase of HTS devices is changed to normal state, so called, quench. In this case, since resistance of HTS is increased abruptly, it can not be avoidable to damage the whole apparatus. In this study, quench detector to protect HTS devices was proposed. We designed the quench detecting circuit and tested the performance of the circuit. The detecting circuit was consisted of Op-Amp and low pass filter etc, to detect very low voltage around $1{\mu}V$. The circuit detected effectively the low voltage when over current is applied to HTS tapes. At the next step, we are going to apply and test the circuit to protect the prototype HTS cable.

• Journal of the Korean Society of Safety
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• v.24 no.3
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• pp.13-18
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• 2009

This paper is purposed to develop DAQ H/W, S/W and DB which can be used in developing electrical fire alarm system or in analyzing electrical fire cause, by detecting and monitoring precursor signals which have high possibility leading to electrical fire on electrical distribution wires. In this paper, developed was DAQ H/W adopting the C8051FXXX CPU which can analyze the measurement signals of current and voltage in electrical distribution wires, other CPU was investigated in view of the best digital sampling rate on the basis of previous researches for electrical fire alarm system. Also, the S/W which can interface with DAQ H/W's communication protocol and can be applied for electrical fire causes analysis, are embodied by LabVIEW. The combined DAQ H/W and S/W could analyze efficiently normal as well as abnormal electrical signals such as RMS value, instantaneous value of current and voltage, frequency signals etc, on the electrical wires. Also, DB system was constructed for recording various analysis results for precursor signals including voltage and current signals. The results by simulator and experiment showed that the suggested scheme with DAQ H/W, S/W and DB in this paper has high usability.

• Journal of Magnetics
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• v.21 no.1
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• pp.57-60
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• 2016

Non Destructive Testing (NDT) methods that are capable of detecting the wall thinning and defects through insulation and cladding sheets are necessary. In this study we developed a Pulsed Eddy Current (PEC) system to detect wall thinning of ferro magnetic steel pipes covered with 95 mm thick fiber glass thermal insulator and shielded with aluminum plate of thickness 0.4 mm. In order to confirm the thickness change due to wall thinning, two different sensors, a hall sensor and a search coil sensor were used as a detecting element. In both the cases, the experimental data indicates a considerable change in the detected pulse corresponding to the change in sample thickness. The thickness of the tube was made to change such as 2.5 mm, 5 mm and 8 mm from the inner surface to simulate wall thinning. Fast Fourier Transform (FFT) was calculated using window approach and the results were summarized which shows a clear identification of thickness change in the test specimen by comparing the magnitude spectra.